Direct confirmation of the radial-velocity planet β Pictoris c
Genzel, R.; Sturm, E.; Tacconi, L. J.; Henning, T.; Girard, J.; Brandner, W.; Kervella, P.; Gendron, E.; Gillessen, S.; van Dishoeck, E. F.; Eisenhauer, F.; Abuter, R.; Lacour, S.; Benisty, M.; Boccaletti, A.; Keppler, M.; Maire, A. -L.; Stolker, T.; Lagrange, A. -M.; de Zeeuw, P. T.; Grandjean, A.; Beust, H.; Rodet, L.; Rubini, P.; Bonnefoy, M.; Eckart, A.; Charnay, B.; Vigan, A.; Mouillet, D.; Cantalloube, F.; Blunt, S.; Mérand, A.; Müller, A.; Wang, J.; Haubois, X.; Ott, T.; Paumard, T.; Perrin, G.; Pfuhl, O.; Kreidberg, L.; Christiaens, V.; Scheithauer, S.; Monnier, J. D.; Asensio-Torres, R.; Wiezorrek, E.; Wieprecht, E.; Hinkley, S.; Garcia Lopez, R.; Pueyo, L.; Kammerer, J.; Drescher, A.; Garcia, P.; Horrobin, M.; Houllé, M.; Le Bouquin, J. -B.; Nowak, M.; Otten, G.; Shangguan, J.; Straubmeier, C.; Widmann, F.; Woillez, J.; Paladini, C.; Perraut, K.; Duvert, G.; Mollière, P.; Amorim, A.; Choquet, E.; Rousset, G.; Clénet, Y.; Heißel, G.; Hippler, S.; Jocou, L.; Léna, P.; Straub, O.; Vincent, F.; Gao, F.; Gardner, T.; Ward-Duong, K.; Rameau, J.; Bonnet, H.; Coudé Du Foresto, V.; Cridland, A.; Dembet, R.; Dexter, J.; Hubert, Z.; Lapeyrère, V.; Nasedkin, E.; Stadler, J.; von Fellenberg, S. D.; GRAVITY Collaboration; Bauböck, M.; Berger, J. P.; Jiménez-Rosales, A.; Rodríguez-Coira, G.; Kulikauskas, M.
United Kingdom, France, Germany, United States, Switzerland, Portugal, Australia, Netherlands, Ireland, Chile, Belgium
Abstract
Context. Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.
Aims: Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.
Methods: We observed the recently-discovered giant planet β Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.
Results: This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of T = 1250 ± 50 K and a dynamical mass of M = 8.2 ± 0.8 MJup. At 18.5 ± 2.5 Myr, this puts β Pic c close to a `hot start' track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (MK = 14.3 ± 0.1) favours a core accretion scenario.
Conclusions: We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.